The torsion of the proximal femur in cementless total hip arthroplasty: a 3-dimensional evaluation.

INTRODUCTION: The anatomy of the proximal femur at the time of total hip arthroplasty has been widely studied but the horizontal plane was never considered, or only limited to the torsion of the femoral neck. METHODS: Using CT-scan images from a group of 178 patients scheduled for cementless total hip arthroplasty (THA), we analysed the evolution of the torsion of the proximal femoral metaphysis, in reference to the posterior bicondylar plane of the femur. The evolution of the torsion, between 20 mm below the centre of the lesser trochanter and 20 mm above, was evaluated. RESULTS: In cases of primary osteoarthritis, osteonecrosis, rheumatoid arthritis and epiphysiolysis capitis femoris, the mean torsion decreased from 46° to 20° without significant differences in average values between the different diagnoses, but important individual variations were found. In the groups of dysplasia and congenital hip dislocation, the torsion values were significantly higher, decreasing in mean from 59° to 25° and 63° to 34° respectively, and with important individual variations. CONCLUSIONS: These data are important when using cementless femoral stems, since an ideal fit-and-fill in the proximal femur zone has been shown to positively influence bone ingrowth of the stem. However, a strict adaptation of the stem to the medullary canal, without considering its torsion, can lead to an increased or decreased torsion of the prosthesis neck and thus to an instability of the arthroplasty. For these reasons, if a perfect adaptation of the stem to the intramedullary anatomy and an optimal reconstruction of the extramedullary anatomy are to be achieved, 3-dimensional planning should ideally be obtained for every patient. This will allow the best stem choice adapted to every single patient and every kind of anatomy.

Modern unicompartmental knee arthroplasty with cement: a concise follow-up, at a mean of twenty years, of a previous report.

We previously evaluated the three to ten-year results of 160 consecutive unicompartmental knee arthroplasties that had been performed by two surgeons in 147 patients with use of the cemented metal-backed Miller-Galante prosthesis. The average age of the patients at the time of the index procedure was sixty-six years. The purpose of the present study was to report the updated results of this series after a mean duration of follow-up of twenty years. Sixty-two patients (seventy knees) were living, and seven had been lost to follow-up. Eleven knees had undergone conversion to total knee arthroplasty, three had had an addition of a patellofemoral prosthesis, and five had had polyethylene exchange. Ten knees had had revision since the three to ten-year evaluation. The reasons for revision included progression of osteoarthritis in twelve knees, aseptic loosening (which had been absent at the three to ten-year evaluation) in two knees, and polyethylene wear (which was treated with liner exchange at an average of twelve years) in five knees. The average clinical and functional Knee Society scores were 91 and 88 points, respectively, at the time of the latest follow-up. The average flexion was 127° (range, 80° to 145°). We concluded that modern cemented metal-backed unicompartmental implants, evaluated at a mean of twenty years of follow-up in patients with osteoarthritis that was limited to one tibiofemoral compartment of the knee, provided durable pain relief and long-term restoration of knee function without compromising future conversion to conventional total knee arthroplasty.

The outcome of rotating-platform total knee arthroplasty with cement at a minimum of ten years of follow-up.

BACKGROUND: Durable, long-term results have been reported for patients managed with first-generation mobile-bearing total knee arthroplasty. Second-generation mobile-bearing total knee arthroplasty has been introduced to enhance instrumentation, to increase flexion, and to improve functional outcome, but, to our knowledge, no long-term results are available. METHODS: From May 1999 to June 2000, 116 consecutive rotating-platform total knee arthroplasties were performed by the two senior authors in 112 patients with use of the LPS-Flex Mobile cemented prosthesis, which was implanted with a measured resection technique. The patella was resurfaced in every knee. The average age of the patients at the time of surgery was sixty-nine years (range, thirty-seven to eighty-five years), and seventy-seven patients (eighty knees) were women. The predominant diagnosis was osteoarthritis. The clinical and radiographic evaluation was performed with use of the Knee Society rating system. The level of activity and patient-reported functional outcome were evaluated with use of the University of California at Los Angeles (UCLA) score and the Knee injury and Osteoarthritis Outcome Score (KOOS), respectively. RESULTS: The average duration of follow-up was 10.6 years (range, ten to 11.8 years). Three patients were lost to follow-up, and five patients died of causes unrelated to knee arthroplasty. Two knees were revised, one because of infection and one because of failure of the medial collateral ligament. Kaplan-Meier survivorship analysis showed an implant survival rate of 98.3% at ten years. For the 104 patients (108 knees) who were evaluated at a minimum of ten years, the average Knee Society knee and function scores improved from 34 to 94 points and from 55 to 88 points, respectively, at the time of the latest follow-up. There was no periprosthetic osteolysis and no evidence of implant loosening on follow-up radiographs. The average knee flexion was 117° preoperatively and 128° at the time of the latest follow-up evaluation. At the time of the latest follow-up, the KOOS quality-of-life score was significantly better for patients with >125° of flexion (p = 0.00034). CONCLUSIONS: This study demonstrated durable clinical and radiographic results at a minimum of ten years after total knee replacement with a second-generation, cemented, rotating-platform, posterior-stabilized total knee prosthesis. According to the functional outcome results obtained in this study, we believe that this design is a valuable option for active patients undergoing total knee arthroplasty.

Survival of bicompartmental knee arthroplasty at 5 to 23 years.

UNLABELLED: Recent literature suggests patients achieve substantial short-term functional improvement after combined bicompartmental implants but longer-term durability has not been documented. We therefore asked whether (1) bicompartmental arthroplasty (either combined medial unicompartmental knee arthroplasty (UKA) and femoropatellar arthroplasty (PFA) or medial UKA/PFA, or combined medial and lateral UKA or bicompartmental UKA) reliably improved Knee Society pain and function scores; (2) bicompartmental arthroplasty was durable (survivorship, radiographic loosening, or symptomatic disease progression); (3) we could achieve durable alignment; and (4) the arthritis would progress in the unresurfaced compartment. We retrospectively reviewed 84 patients (100 knees) with bicompartmental UKA and 71 patients (77 knees) with medial UKA/PFA. Clinical and radiographic evaluations were performed at a minimum followup of 5 years (mean, 12 years; range, 5-23 years). Bicompartmental arthroplasty reliably alleviated pain and improved function. Prosthesis survivorship at 17 years was 78% in the bicompartmental UKA group and 54% in the medial UKA/PFA group. The high revision rate, compared with total knee arthroplasty, may be related to several factors such as implant design, patient selection, crude or absent instrumentation, or component malalignment, which can all contribute to the relatively high failure rate in this series. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Long-term results with a lateral unicondylar replacement.

UNLABELLED: While the literature suggests lateral unicondylar knee arthroplasty (UKA) improves function in the short- and medium-term, it is less clear on longer-term function. We asked (1) whether lateral UKA improved longer-term Knee Society scores and return to previous activity level); (2) whether there were any concerning longer-term radiographic findings (the Knee Society roentgenographic evaluation and scoring system); and (3) whether lateral UKA was durable as measured by survivorship to revision at 10 and 16 years. We retrospectively reviewed 39 patients with 40 lateral cemented metal-backed UKA. The patients had a mean age of 61 years at surgery. The etiologies were primary osteoarthritis in 24 knees, posttraumatic in 12 cases, and osteonecrosis in four cases. We performed clinical and radiographic evaluations at a minimum followup of 3 years (mean, 12.6 years; range, 3-23 years). Prostheses survivorship was 92% at 10 years and 84% at 16 years. Despite the limited number of indications and technical considerations, our data suggest lateral UKA is a reasonable alternative for isolated lateral femorotibial compartment disease. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Evaluation of the hip center in total hip arthroplasty for old developmental dysplasia.

We describe the problems with positioning the hip center according to the severity of dislocation in 97 cementless total hip arthroplasty for developmental dysplasia of the hip. The mean location of the hip center from the interteardrop was 30.4 +/- 8.7 mm horizontally and 23.4 +/- 5.4 mm vertically. The presence of a limp correlated with a superior placement of the cup. Four cups were revised, 2 of which with a significant high hip center. The survival rate of the acetabular component was 95% at 12 years. Craniopodal repositioning was easy in class 1. In class 2, the cup was the largest. In class 3, the greatest variations of the hip center were found. In class 4, the smallest implants were necessary for positioning in the true acetabulum.

Anatomy of the dysplastic hip and consequences for total hip arthroplasty.

Total hip arthroplasty in dysplastic hips is challenging because of the modified anatomy of the proximal femur and acetabulum. We studied three-dimensional anatomic parameters in 247 dysplastic hips from 218 adult patients using radiographs and computed tomography, and analyzed the consequences for total hip arthroplasty. A cohort of 310 primary osteoarthritic hips was used as a control group. According to the classification of Crowe et al, 78 of the dislocated hips were graded Class I, 26 as Class II, 20 as Class III or IV, and 169 dysplastic hips had no subluxation. Compared with primary osteoarthritis, the intramedullary femoral canal had reduced mediolateral and anteroposterior dimensions. With high grade subluxations the femoral neck shaft angle decreased but with low grades, especially in Class II, the neck shaft angle increased. The proximal femur had more anteversion with individual variations ranging from 1 degrees to 80 degrees. The true acetabulum had a reduced anteroposterior diameter. The large individual morphologic variability across all levels of dysplastic hips suggests the femoral prosthesis cannot be chosen on the basis of the severity of the subluxation alone.

Unicompartmental knee arthroplasty for avascular osteonecrosis.

UNLABELLED: The data analyzing clinical and radiological outcomes after modern unicompartmental knee arthroplasty (UKA) for spontaneous and secondary avascular osteonecrosis are limited. We determined whether: (1) UKA for osteonecrosis was as reliable for alleviating pain and improving function (measured by Knee Society scores) as it is for osteoarthritis, (2) lower limb alignment could be restored after UKA for osteonecrosis, and (3) UKA for osteonecrosis is as durable as UKA for osteoarthritis (measured by survivorship at 12 years). We retrospectively reviewed 30 patients (31 knees) with osteonecrosis; 21 knees had spontaneous osteonecrosis and 10 had secondary osteonecrosis. Mean patient age was 71 years. Clinical and radiological evaluations were performed by an independent observer at a minimum followup of 3 years (mean, 7 years; range, 3-16 years). Reliable pain relief and function improvement were obtained in 30 knees (96%). Restoration of an appropriate lower-limb mechanical axis was achieved for 27 knees (88%). The Kaplan-Meier survivorship was 96.7% at 12 years. Our data suggest UKA is a reasonable solution for restoring clinical function and radiological lower-limb alignment for spontaneous or secondary osteonecrosis limited to one compartment of the knee, with a durable survivorship. LEVEL OF EVIDENCE: Level IV, retrospective study. See the Guidelines for Authors for a complete description of levels of evidence.

Patellofemoral arthroplasty: an update.

UNLABELLED: The rationale for presenting this updated study is to report long-term clinical and survival results of patellofemoral arthroplasty and to ascertain whether the preoperative diagnosis influenced outcomes and therefore indications. We retrospectively updated a previous evaluation of 66 patients who had unilateral patellofemoral arthroplasty between 1972 and 1990. The mean age of the patients at the initial surgery was 57 years (range, 21-82 years). The patients had an average followup of 16.2 years (range, 12-20 years). Preoperative diagnosis included instability, fracture, and primary arthritis. Revision surgery was done in 14 patients for femorotibial osteoarthritis, in 11 for loosening, and in four for stiffness. Survivorship was 58% at 16 years. The knee function score improved from 40 points preoperatively to 81 points at last followup. The best results were in patients with preoperative instability and corrected alignment of the extensor mechanism. Stiffness occurred only in those patients with osteoarthritis from previous fracture. Progressive degeneration of the tibiofemoral joint was noted mainly in the primary osteoarthritis etiologic group. This long-term evaluation of patellofemoral arthroplasty showed the importance of patient selection while excluding knees with significant frontal tibiofemoral malalignment. LEVEL OF EVIDENCE: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Three-dimensional computed cementless custom femoral stems in young patients: midterm followup.

UNLABELLED: We prospectively evaluated the results of our custom cementless femoral stems to ascertain whether this technology produced reasonable clinical function, complication rates, and loosening rates at midterm. Fifty-seven consecutive patients had surgery in 62 hips for primary osteoarthritis at a mean age of 57 years using a three-dimensional computed custom cementless stem. Patients were reviewed at a mean followup of 94.9 months. At review, the mean Harris hip score was 98.8 points (range, 84-100) compared with 61.1 (range, 28-78) points preoperatively. No patient complained of thigh pain. No migration or subsidence was observed. All stems were considered stable according to the radiographic criteria defined by Engh et al. There were no dislocations, no infections, and no reoperations. Our results are comparable with published results from clinical and radiologic points of view. Two problems remain unsolved: the price of a custom stem is twice as expensive as a standard stem; and we need longer term results before definitely recommending this technology as a reasonable alternative to current arthroplasties in younger patients. The data support the continued exploration of this technology with controlled clinical followup. LEVEL OF EVIDENCE: Therapeutic study, Level II-1 (prospective cohort study). See the Guidelines to Authors for a complete description of levels of evidence.

Relationship of relapsing hip prosthesis infection by Staphylococcus aureus with gamma interferon deficiency.

Infections complicate 0.5 to 1% of surgeries for total hip prostheses. Staphylococcus species are the most common etiological agents. The role of host factors in the persistence of such infections despite appropriate therapy has yet to be determined. We report the defective immune response characterized by oversecretion of tumor necrosis factor and interleukin 10 and by undersecretion of gamma interferon in such a patient. Further study may determine the prevalence of such deficits and the most appropriate therapy for these patients.

Modern unicompartmental knee arthroplasty with cement: a three to ten-year follow-up study.

BACKGROUND: Unicompartmental arthroplasty is a treatment alternative when only one compartment of the knee is affected with arthritis, but the reported results of this procedure have been variable. The purpose of the present study was to evaluate the results of a modern unicompartmental knee arthroplasty performed with use of a cemented metal-backed prosthesis and surgical instrumentation comparable with that used for total knee replacement. METHODS: The indications for the procedure were osteonecrosis or osteoarthritis associated with full-thickness loss of cartilage that was limited to one tibiofemoral compartment as evaluated on standing and stress radiographs. One hundred and sixty consecutive cemented metal-backed Miller-Galante prostheses in 147 patients were evaluated after a mean duration of follow-up of sixty-six months (range, thirty-six to 112 months). The mean age of the patients at the time of the index procedure was sixty-six years. RESULTS: Three knees were revised because of progression of osteoarthritis in the patellofemoral joint (two knees) or the lateral tibiofemoral compartment (one knee). Two knees had revision of the polyethylene liner. The average Hospital for Special Surgery knee score improved from 59 points preoperatively to 96 points at the time of the review. According to Kaplan-Meier analysis, the ten-year survival rate (with twenty-nine knees at risk) was 94% +/- 3% with revision for any reason or radiographic loosening as the end point. CONCLUSIONS: A modern unicompartmental knee arthroplasty is a valid alternative for patients with unicompartmental tibiofemoral noninflammatory disease. The patient selection must be strict with regard to the status of the patellofemoral joint. The preoperative planning includes stress radiographs to assess the correction of the deformity and the status of the uninvolved compartment. Continued long-term follow-up is necessary to evaluate long-term polyethylene wear.